// The idea is to remove redundant copies.
// v1->v2 F=0
// (use v2 s/v2/v1/)*
// set v1 F=1
// use v2 return fail (v1->v2 move must remain)
// -----------------
// v1->v2 F=0
// (use v2 s/v2/v1/)*
// set v1 F=1
// set v2 return success (caller can remove v1->v2 move)
func copyprop(r *gc.Flow) bool {
p := r.Prog
canSub := false
switch p.As {
case s390x.AFMOVS, s390x.AFMOVD, s390x.AMOVD:
canSub = true
default:
for rr := gc.Uniqp(r); rr != nil; rr = gc.Uniqp(rr) {
if gc.Uniqs(rr) == nil {
break
}
switch copyu(rr.Prog, &p.From, nil) {
case _Read, _None:
continue
}
// write
if rr.Prog.As == p.As {
canSub = true
}
break
}
}
if !canSub {
return false
}
if copyas(&p.From, &p.To) {
return true
}
gactive++
return copy1(&p.From, &p.To, r.S1, 0)
}
// the idea is to substitute
// one register for another
// from one MOV to another
// MOV a, R1
// ADD b, R1 / no use of R2
// MOV R1, R2
// would be converted to
// MOV a, R2
// ADD b, R2
// MOV R2, R1
// hopefully, then the former or latter MOV
// will be eliminated by copy propagation.
//
// r0 (the argument, not the register) is the MOV at the end of the
// above sequences. subprop returns true if it modified any instructions.
func subprop(r0 *gc.Flow) bool {
p := r0.Prog
v1 := &p.From
if !isReg(v1) {
return false
}
v2 := &p.To
if !isReg(v2) {
return false
}
cast := false
switch p.As {
case s390x.AMOVW, s390x.AMOVWZ,
s390x.AMOVH, s390x.AMOVHZ,
s390x.AMOVB, s390x.AMOVBZ:
cast = true
}
for r := gc.Uniqp(r0); r != nil; r = gc.Uniqp(r) {
if gc.Uniqs(r) == nil {
break
}
p = r.Prog
switch copyu(p, v1, nil) {
case _Write, _ReadWriteDiff:
if p.As == obj.ACALL {
return false
}
if (!cast || p.As == r0.Prog.As) && p.To.Type == v1.Type && p.To.Reg == v1.Reg {
copysub(&p.To, v1, v2)
for r = gc.Uniqs(r); r != r0; r = gc.Uniqs(r) {
p = r.Prog
copysub(&p.From, v1, v2)
copysub1(p, v1, v2)
copysub(&p.To, v1, v2)
}
v1.Reg, v2.Reg = v2.Reg, v1.Reg
return true
}
if cast {
return false
}
case _ReadWriteSame:
if cast {
return false
}
}
if copyu(p, v2, nil) != _None {
return false
}
}
return false
}
// is reg guaranteed to be truncated by a previous L instruction?
func prevl(r0 *gc.Flow, reg int16) bool {
for r := gc.Uniqp(r0); r != nil; r = gc.Uniqp(r) {
p := r.Prog
if p.To.Type == obj.TYPE_REG && p.To.Reg == reg {
flags := progflags(p)
if flags&gc.RightWrite != 0 {
if flags&gc.SizeL != 0 {
return true
}
return false
}
}
}
return false
}
// removeLoadHitStores trys to remove loads that take place
// immediately after a store to the same location. Returns
// true if load-hit-stores were removed.
//
// For example:
// MOVD R1, 0(R15)
// MOVD 0(R15), R2
// Would become:
// MOVD R1, 0(R15)
// MOVD R1, R2
func removeLoadHitStores(r *gc.Flow) int {
n := 0
for ; r != nil; r = r.Link {
p := r.Prog
if !isStore(p) {
continue
}
for rr := gc.Uniqs(r); rr != nil; rr = gc.Uniqs(rr) {
pp := rr.Prog
if gc.Uniqp(rr) == nil {
break
}
if pp.As == obj.ANOP {
continue
}
if isLoad(pp) && sameStackMem(&p.To, &pp.From) {
if size(p.As) >= size(pp.As) && isGPR(&p.From) == isGPR(&pp.To) {
pp.From = p.From
}
}
if !isMove(pp) || isStore(pp) {
break
}
if copyau(&p.From, &pp.To) {
break
}
}
}
return n
}
/*
* findinc finds ADD instructions with a constant
* argument which falls within the immed_12 range.
*/
func findinc(r *gc.Flow, r2 *gc.Flow, v *obj.Addr) *gc.Flow {
var r1 *gc.Flow
var p *obj.Prog
for r1 = gc.Uniqs(r); r1 != nil && r1 != r2; r, r1 = r1, gc.Uniqs(r1) {
if gc.Uniqp(r1) != r {
return nil
}
switch copyu(r1.Prog, v, nil) {
case 0: /* not touched */
continue
case 4: /* set and used */
p = r1.Prog
if p.As == arm.AADD {
if isdconst(&p.From) {
if p.From.Offset > -4096 && p.From.Offset < 4096 {
return r1
}
}
}
fallthrough
default:
return nil
}
}
return nil
}
/*
* findpre returns the last instruction mentioning v
* before r. It must be a set, and there must be
* a unique path from that instruction to r.
*/
func findpre(r *gc.Flow, v *obj.Addr) *gc.Flow {
var r1 *gc.Flow
for r1 = gc.Uniqp(r); r1 != nil; r, r1 = r1, gc.Uniqp(r1) {
if gc.Uniqs(r1) != r {
return nil
}
switch copyu(r1.Prog, v, nil) {
case 1, /* used */
2: /* read-alter-rewrite */
return nil
case 3, /* set */
4: /* set and used */
return r1
}
}
return nil
}
func conprop(r0 *gc.Flow) {
var p *obj.Prog
var t int
p0 := (*obj.Prog)(r0.Prog)
v0 := (*obj.Addr)(&p0.To)
r := (*gc.Flow)(r0)
loop:
r = gc.Uniqs(r)
if r == nil || r == r0 {
return
}
if gc.Uniqp(r) == nil {
return
}
p = r.Prog
t = copyu(p, v0, nil)
switch t {
case 0, // miss
1: // use
goto loop
case 2, // rar
4: // use and set
break
case 3: // set
if p.As == p0.As {
if p.From.Type == p0.From.Type {
if p.From.Reg == p0.From.Reg {
if p.From.Node == p0.From.Node {
if p.From.Offset == p0.From.Offset {
if p.From.Scale == p0.From.Scale {
if p.From.Type == obj.TYPE_FCONST && p.From.Val.(float64) == p0.From.Val.(float64) {
if p.From.Index == p0.From.Index {
excise(r)
goto loop
}
}
}
}
}
}
}
}
}
}
// copy1 replaces uses of v2 with v1 starting at r and returns true if
// all uses were rewritten.
func copy1(v1 *obj.Addr, v2 *obj.Addr, r *gc.Flow, f int) bool {
if uint32(r.Active) == gactive {
return true
}
r.Active = int32(gactive)
for ; r != nil; r = r.S1 {
p := r.Prog
if f == 0 && gc.Uniqp(r) == nil {
// Multiple predecessors; conservatively
// assume v1 was set on other path
f = 1
}
t := copyu(p, v2, nil)
switch t {
case _ReadWriteSame:
return false
case _Write:
return true
case _Read, _ReadWriteDiff:
if f != 0 {
return false
}
if copyu(p, v2, v1) != 0 {
return false
}
if t == _ReadWriteDiff {
return true
}
}
if f == 0 {
switch copyu(p, v1, nil) {
case _ReadWriteSame, _ReadWriteDiff, _Write:
f = 1
}
}
if r.S2 != nil {
if !copy1(v1, v2, r.S2, f) {
return false
}
}
}
return true
}
/*
* The idea is to remove redundant constants.
* $c1->v1
* ($c1->v2 s/$c1/v1)*
* set v1 return
* The v1->v2 should be eliminated by copy propagation.
*/
func constprop(c1 *obj.Addr, v1 *obj.Addr, r *gc.Flow) {
if gc.Debug['P'] != 0 {
fmt.Printf("constprop %v->%v\n", gc.Ctxt.Dconv(c1), gc.Ctxt.Dconv(v1))
}
var p *obj.Prog
for ; r != nil; r = r.S1 {
p = r.Prog
if gc.Debug['P'] != 0 {
fmt.Printf("%v", p)
}
if gc.Uniqp(r) == nil {
if gc.Debug['P'] != 0 {
fmt.Printf("; merge; return\n")
}
return
}
if p.As == arm.AMOVW && copyas(&p.From, c1) {
if gc.Debug['P'] != 0 {
fmt.Printf("; sub%v/%v", gc.Ctxt.Dconv(&p.From), gc.Ctxt.Dconv(v1))
}
p.From = *v1
} else if copyu(p, v1, nil) > 1 {
if gc.Debug['P'] != 0 {
fmt.Printf("; %vset; return\n", gc.Ctxt.Dconv(v1))
}
return
}
if gc.Debug['P'] != 0 {
fmt.Printf("\n")
}
if r.S2 != nil {
constprop(c1, v1, r.S2)
}
}
}
/*
* the idea is to substitute
* one register for another
* from one MOV to another
* MOV a, R0
* ADD b, R0 / no use of R1
* MOV R0, R1
* would be converted to
* MOV a, R1
* ADD b, R1
* MOV R1, R0
* hopefully, then the former or latter MOV
* will be eliminated by copy propagation.
*/
func subprop(r0 *gc.Flow) bool {
p := r0.Prog
v1 := &p.From
if !regtyp(v1) {
return false
}
v2 := &p.To
if !regtyp(v2) {
return false
}
for r := gc.Uniqp(r0); r != nil; r = gc.Uniqp(r) {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\t? %v\n", r.Prog)
}
if gc.Uniqs(r) == nil {
break
}
p = r.Prog
if p.As == obj.AVARDEF || p.As == obj.AVARKILL {
continue
}
if p.Info.Flags&gc.Call != 0 {
return false
}
if p.Info.Reguse|p.Info.Regset != 0 {
return false
}
if (p.Info.Flags&gc.Move != 0) && (p.Info.Flags&(gc.SizeL|gc.SizeQ|gc.SizeF|gc.SizeD) != 0) && p.To.Type == v1.Type && p.To.Reg == v1.Reg {
copysub(&p.To, v1, v2, 1)
if gc.Debug['P'] != 0 {
fmt.Printf("gotit: %v->%v\n%v", gc.Ctxt.Dconv(v1), gc.Ctxt.Dconv(v2), r.Prog)
if p.From.Type == v2.Type && p.From.Reg == v2.Reg {
fmt.Printf(" excise")
}
fmt.Printf("\n")
}
for r = gc.Uniqs(r); r != r0; r = gc.Uniqs(r) {
p = r.Prog
copysub(&p.From, v1, v2, 1)
copysub(&p.To, v1, v2, 1)
if gc.Debug['P'] != 0 {
fmt.Printf("%v\n", r.Prog)
}
}
t := int(v1.Reg)
v1.Reg = v2.Reg
v2.Reg = int16(t)
if gc.Debug['P'] != 0 {
fmt.Printf("%v last\n", r.Prog)
}
return true
}
if copyau(&p.From, v2) || copyau(&p.To, v2) {
break
}
if copysub(&p.From, v1, v2, 0) != 0 || copysub(&p.To, v1, v2, 0) != 0 {
break
}
}
return false
}
/*
* ASLL x,y,w
* .. (not use w, not set x y w)
* AXXX w,a,b (a != w)
* .. (not use w)
* (set w)
* ----------- changed to
* ..
* AXXX (x<<y),a,b
* ..
*/
func shiftprop(r *gc.Flow) bool {
p := (*obj.Prog)(r.Prog)
if p.To.Type != obj.TYPE_REG {
if gc.Debug['P'] != 0 {
fmt.Printf("\tBOTCH: result not reg; FAILURE\n")
}
return false
}
n := int(int(p.To.Reg))
a := obj.Addr(obj.Addr{})
if p.Reg != 0 && p.Reg != p.To.Reg {
a.Type = obj.TYPE_REG
a.Reg = p.Reg
}
if gc.Debug['P'] != 0 {
fmt.Printf("shiftprop\n%v", p)
}
r1 := (*gc.Flow)(r)
var p1 *obj.Prog
for {
/* find first use of shift result; abort if shift operands or result are changed */
r1 = gc.Uniqs(r1)
if r1 == nil {
if gc.Debug['P'] != 0 {
fmt.Printf("\tbranch; FAILURE\n")
}
return false
}
if gc.Uniqp(r1) == nil {
if gc.Debug['P'] != 0 {
fmt.Printf("\tmerge; FAILURE\n")
}
return false
}
p1 = r1.Prog
if gc.Debug['P'] != 0 {
fmt.Printf("\n%v", p1)
}
switch copyu(p1, &p.To, nil) {
case 0: /* not used or set */
if (p.From.Type == obj.TYPE_REG && copyu(p1, &p.From, nil) > 1) || (a.Type == obj.TYPE_REG && copyu(p1, &a, nil) > 1) {
if gc.Debug['P'] != 0 {
fmt.Printf("\targs modified; FAILURE\n")
}
return false
}
continue
case 3: /* set, not used */
{
if gc.Debug['P'] != 0 {
fmt.Printf("\tBOTCH: noref; FAILURE\n")
}
return false
}
}
break
}
/* check whether substitution can be done */
switch p1.As {
default:
if gc.Debug['P'] != 0 {
fmt.Printf("\tnon-dpi; FAILURE\n")
}
return false
case arm.AAND,
arm.AEOR,
arm.AADD,
arm.AADC,
arm.AORR,
arm.ASUB,
arm.ASBC,
arm.ARSB,
arm.ARSC:
if int(p1.Reg) == n || (p1.Reg == 0 && p1.To.Type == obj.TYPE_REG && int(p1.To.Reg) == n) {
if p1.From.Type != obj.TYPE_REG {
if gc.Debug['P'] != 0 {
fmt.Printf("\tcan't swap; FAILURE\n")
}
return false
}
p1.Reg = p1.From.Reg
p1.From.Reg = int16(n)
switch p1.As {
case arm.ASUB:
p1.As = arm.ARSB
case arm.ARSB:
p1.As = arm.ASUB
case arm.ASBC:
p1.As = arm.ARSC
case arm.ARSC:
p1.As = arm.ASBC
}
if gc.Debug['P'] != 0 {
fmt.Printf("\t=>%v", p1)
}
}
fallthrough
case arm.ABIC,
arm.ATST,
arm.ACMP,
arm.ACMN:
if int(p1.Reg) == n {
if gc.Debug['P'] != 0 {
fmt.Printf("\tcan't swap; FAILURE\n")
}
return false
}
if p1.Reg == 0 && int(p1.To.Reg) == n {
if gc.Debug['P'] != 0 {
fmt.Printf("\tshift result used twice; FAILURE\n")
}
return false
}
// case AMVN:
if p1.From.Type == obj.TYPE_SHIFT {
if gc.Debug['P'] != 0 {
fmt.Printf("\tshift result used in shift; FAILURE\n")
}
return false
}
if p1.From.Type != obj.TYPE_REG || int(p1.From.Reg) != n {
if gc.Debug['P'] != 0 {
fmt.Printf("\tBOTCH: where is it used?; FAILURE\n")
}
return false
}
}
/* check whether shift result is used subsequently */
p2 := (*obj.Prog)(p1)
if int(p1.To.Reg) != n {
var p1 *obj.Prog
for {
r1 = gc.Uniqs(r1)
if r1 == nil {
if gc.Debug['P'] != 0 {
fmt.Printf("\tinconclusive; FAILURE\n")
}
return false
}
p1 = r1.Prog
if gc.Debug['P'] != 0 {
fmt.Printf("\n%v", p1)
}
switch copyu(p1, &p.To, nil) {
case 0: /* not used or set */
continue
case 3: /* set, not used */
break
default: /* used */
if gc.Debug['P'] != 0 {
fmt.Printf("\treused; FAILURE\n")
}
return false
}
break
}
}
/* make the substitution */
p2.From.Reg = 0
o := int(int(p.Reg))
if o == 0 {
o = int(p.To.Reg)
}
o &= 15
switch p.From.Type {
case obj.TYPE_CONST:
o |= int((p.From.Offset & 0x1f) << 7)
case obj.TYPE_REG:
o |= 1<<4 | (int(p.From.Reg)&15)<<8
}
switch p.As {
case arm.ASLL:
o |= 0 << 5
case arm.ASRL:
o |= 1 << 5
case arm.ASRA:
o |= 2 << 5
}
p2.From = obj.Addr{}
p2.From.Type = obj.TYPE_SHIFT
p2.From.Offset = int64(o)
if gc.Debug['P'] != 0 {
fmt.Printf("\t=>%v\tSUCCEED\n", p2)
}
return true
}
func copy1(v1 *obj.Addr, v2 *obj.Addr, r *gc.Flow, f int) bool {
if uint32(r.Active) == gactive {
if gc.Debug['P'] != 0 {
fmt.Printf("act set; return 1\n")
}
return true
}
r.Active = int32(gactive)
if gc.Debug['P'] != 0 {
fmt.Printf("copy %v->%v f=%d\n", gc.Ctxt.Dconv(v1), gc.Ctxt.Dconv(v2), f)
}
var t int
var p *obj.Prog
for ; r != nil; r = r.S1 {
p = r.Prog
if gc.Debug['P'] != 0 {
fmt.Printf("%v", p)
}
if f == 0 && gc.Uniqp(r) == nil {
f = 1
if gc.Debug['P'] != 0 {
fmt.Printf("; merge; f=%d", f)
}
}
t = copyu(p, v2, nil)
switch t {
case 2: /* rar, can't split */
if gc.Debug['P'] != 0 {
fmt.Printf("; %vrar; return 0\n", gc.Ctxt.Dconv(v2))
}
return false
case 3: /* set */
if gc.Debug['P'] != 0 {
fmt.Printf("; %vset; return 1\n", gc.Ctxt.Dconv(v2))
}
return true
case 1, /* used, substitute */
4: /* use and set */
if f != 0 {
if gc.Debug['P'] == 0 {
return false
}
if t == 4 {
fmt.Printf("; %vused+set and f=%d; return 0\n", gc.Ctxt.Dconv(v2), f)
} else {
fmt.Printf("; %vused and f=%d; return 0\n", gc.Ctxt.Dconv(v2), f)
}
return false
}
if copyu(p, v2, v1) != 0 {
if gc.Debug['P'] != 0 {
fmt.Printf("; sub fail; return 0\n")
}
return false
}
if gc.Debug['P'] != 0 {
fmt.Printf("; sub%v/%v", gc.Ctxt.Dconv(v2), gc.Ctxt.Dconv(v1))
}
if t == 4 {
if gc.Debug['P'] != 0 {
fmt.Printf("; %vused+set; return 1\n", gc.Ctxt.Dconv(v2))
}
return true
}
}
if f == 0 {
t = copyu(p, v1, nil)
if f == 0 && (t == 2 || t == 3 || t == 4) {
f = 1
if gc.Debug['P'] != 0 {
fmt.Printf("; %vset and !f; f=%d", gc.Ctxt.Dconv(v1), f)
}
}
}
if gc.Debug['P'] != 0 {
fmt.Printf("\n")
}
if r.S2 != nil {
if !copy1(v1, v2, r.S2, f) {
return false
}
}
}
return true
}
/*
* the idea is to substitute
* one register for another
* from one MOV to another
* MOV a, R0
* ADD b, R0 / no use of R1
* MOV R0, R1
* would be converted to
* MOV a, R1
* ADD b, R1
* MOV R1, R0
* hopefully, then the former or latter MOV
* will be eliminated by copy propagation.
*/
func subprop(r0 *gc.Flow) bool {
p := (*obj.Prog)(r0.Prog)
v1 := (*obj.Addr)(&p.From)
if !regtyp(v1) {
return false
}
v2 := (*obj.Addr)(&p.To)
if !regtyp(v2) {
return false
}
for r := gc.Uniqp(r0); r != nil; r = gc.Uniqp(r) {
if gc.Uniqs(r) == nil {
break
}
p = r.Prog
if p.As == obj.AVARDEF || p.As == obj.AVARKILL {
continue
}
if p.Info.Flags&gc.Call != 0 {
return false
}
// TODO(rsc): Whatever invalidated the info should have done this call.
proginfo(p)
if (p.Info.Flags&gc.CanRegRead != 0) && p.To.Type == obj.TYPE_REG {
p.Info.Flags |= gc.RegRead
p.Info.Flags &^= (gc.CanRegRead | gc.RightRead)
p.Reg = p.To.Reg
}
switch p.As {
case arm.AMULLU,
arm.AMULA,
arm.AMVN:
return false
}
if p.Info.Flags&(gc.RightRead|gc.RightWrite) == gc.RightWrite {
if p.To.Type == v1.Type {
if p.To.Reg == v1.Reg {
if p.Scond == arm.C_SCOND_NONE {
copysub(&p.To, v1, v2, 1)
if gc.Debug['P'] != 0 {
fmt.Printf("gotit: %v->%v\n%v", gc.Ctxt.Dconv(v1), gc.Ctxt.Dconv(v2), r.Prog)
if p.From.Type == v2.Type {
fmt.Printf(" excise")
}
fmt.Printf("\n")
}
for r = gc.Uniqs(r); r != r0; r = gc.Uniqs(r) {
p = r.Prog
copysub(&p.From, v1, v2, 1)
copysub1(p, v1, v2, 1)
copysub(&p.To, v1, v2, 1)
if gc.Debug['P'] != 0 {
fmt.Printf("%v\n", r.Prog)
}
}
t := int(int(v1.Reg))
v1.Reg = v2.Reg
v2.Reg = int16(t)
if gc.Debug['P'] != 0 {
fmt.Printf("%v last\n", r.Prog)
}
return true
}
}
}
}
if copyau(&p.From, v2) || copyau1(p, v2) || copyau(&p.To, v2) {
break
}
if copysub(&p.From, v1, v2, 0) != 0 || copysub1(p, v1, v2, 0) != 0 || copysub(&p.To, v1, v2, 0) != 0 {
break
}
}
return false
}
/*
* the idea is to substitute
* one register for another
* from one MOV to another
* MOV a, R0
* ADD b, R0 / no use of R1
* MOV R0, R1
* would be converted to
* MOV a, R1
* ADD b, R1
* MOV R1, R0
* hopefully, then the former or latter MOV
* will be eliminated by copy propagation.
*/
func subprop(r0 *gc.Flow) bool {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("subprop %v\n", r0.Prog)
}
p := (*obj.Prog)(r0.Prog)
v1 := (*obj.Addr)(&p.From)
if !regtyp(v1) {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tnot regtype %v; return 0\n", gc.Ctxt.Dconv(v1))
}
return false
}
v2 := (*obj.Addr)(&p.To)
if !regtyp(v2) {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tnot regtype %v; return 0\n", gc.Ctxt.Dconv(v2))
}
return false
}
for r := gc.Uniqp(r0); r != nil; r = gc.Uniqp(r) {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\t? %v\n", r.Prog)
}
if gc.Uniqs(r) == nil {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tno unique successor\n")
}
break
}
p = r.Prog
if p.As == obj.AVARDEF || p.As == obj.AVARKILL {
continue
}
if p.Info.Flags&gc.Call != 0 {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tfound %v; return 0\n", p)
}
return false
}
if p.Info.Reguse|p.Info.Regset != 0 {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tfound %v; return 0\n", p)
}
return false
}
if (p.Info.Flags&gc.Move != 0) && (p.Info.Flags&(gc.SizeL|gc.SizeQ|gc.SizeF|gc.SizeD) != 0) && p.To.Type == v1.Type && p.To.Reg == v1.Reg {
copysub(&p.To, v1, v2, 1)
if gc.Debug['P'] != 0 {
fmt.Printf("gotit: %v->%v\n%v", gc.Ctxt.Dconv(v1), gc.Ctxt.Dconv(v2), r.Prog)
if p.From.Type == v2.Type && p.From.Reg == v2.Reg {
fmt.Printf(" excise")
}
fmt.Printf("\n")
}
for r = gc.Uniqs(r); r != r0; r = gc.Uniqs(r) {
p = r.Prog
copysub(&p.From, v1, v2, 1)
copysub(&p.To, v1, v2, 1)
if gc.Debug['P'] != 0 {
fmt.Printf("%v\n", r.Prog)
}
}
t := int(int(v1.Reg))
v1.Reg = v2.Reg
v2.Reg = int16(t)
if gc.Debug['P'] != 0 {
fmt.Printf("%v last\n", r.Prog)
}
return true
}
if copyau(&p.From, v2) || copyau(&p.To, v2) {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tcopyau %v failed\n", gc.Ctxt.Dconv(v2))
}
break
}
if copysub(&p.From, v1, v2, 0) != 0 || copysub(&p.To, v1, v2, 0) != 0 {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tcopysub failed\n")
}
break
}
}
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tran off end; return 0\n")
}
return false
}
// fuseMultiple merges memory loads and stores into load multiple and
// store multiple operations.
//
// Looks for this pattern (sequence of loads or stores):
// MOVD R1, 0(R15)
// MOVD R2, 8(R15)
// MOVD R3, 16(R15)
// Replaces with:
// STMG R1, R3, 0(R15)
func fuseMultiple(r *gc.Flow) int {
n := 0
var fused *obj.Prog
for ; r != nil; r = r.Link {
// If there is a branch into the instruction stream then
// we can't fuse into previous instructions.
if gc.Uniqp(r) == nil {
fused = nil
}
p := r.Prog
isStore := isGPR(&p.From) && isBDMem(&p.To)
isLoad := isGPR(&p.To) && isBDMem(&p.From)
// are we a candidate?
size := int64(0)
switch p.As {
default:
fused = nil
continue
case obj.ANOP:
// skip over nops
continue
case s390x.AMOVW, s390x.AMOVWZ:
size = 4
// TODO(mundaym): 32-bit load multiple is currently not supported
// as it requires sign/zero extension.
if !isStore {
fused = nil
continue
}
case s390x.AMOVD:
size = 8
if !isLoad && !isStore {
fused = nil
continue
}
}
// If we merge two loads/stores with different source/destination Nodes
// then we will lose a reference the second Node which means that the
// compiler might mark the Node as unused and free its slot on the stack.
// TODO(mundaym): allow this by adding a dummy reference to the Node.
if fused == nil ||
fused.From.Node != p.From.Node ||
fused.From.Type != p.From.Type ||
fused.To.Node != p.To.Node ||
fused.To.Type != p.To.Type {
fused = p
continue
}
// check two addresses
ca := func(a, b *obj.Addr, offset int64) bool {
return a.Reg == b.Reg && a.Offset+offset == b.Offset &&
a.Sym == b.Sym && a.Name == b.Name
}
switch fused.As {
default:
fused = p
case s390x.AMOVW, s390x.AMOVWZ:
if size == 4 && fused.From.Reg+1 == p.From.Reg && ca(&fused.To, &p.To, 4) {
fused.As = s390x.ASTMY
fused.Reg = p.From.Reg
excise(r)
n++
} else {
fused = p
}
case s390x.AMOVD:
if size == 8 && fused.From.Reg+1 == p.From.Reg && ca(&fused.To, &p.To, 8) {
fused.As = s390x.ASTMG
fused.Reg = p.From.Reg
excise(r)
n++
} else if size == 8 && fused.To.Reg+1 == p.To.Reg && ca(&fused.From, &p.From, 8) {
fused.As = s390x.ALMG
fused.Reg = fused.To.Reg
fused.To.Reg = p.To.Reg
excise(r)
n++
} else {
fused = p
}
case s390x.ASTMG, s390x.ASTMY:
if (fused.As == s390x.ASTMY && size != 4) ||
(fused.As == s390x.ASTMG && size != 8) {
fused = p
continue
}
offset := size * int64(fused.Reg-fused.From.Reg+1)
if fused.Reg+1 == p.From.Reg && ca(&fused.To, &p.To, offset) {
fused.Reg = p.From.Reg
excise(r)
n++
} else {
fused = p
}
case s390x.ALMG:
offset := 8 * int64(fused.To.Reg-fused.Reg+1)
if size == 8 && fused.To.Reg+1 == p.To.Reg && ca(&fused.From, &p.From, offset) {
fused.To.Reg = p.To.Reg
excise(r)
n++
} else {
fused = p
}
}
}
return n
}
func peep(firstp *obj.Prog) {
g := gc.Flowstart(firstp, nil)
if g == nil {
return
}
gactive = 0
var p *obj.Prog
var r *gc.Flow
var t obj.As
loop1:
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
gc.Dumpit("loop1", g.Start, 0)
}
t = 0
for r = g.Start; r != nil; r = r.Link {
p = r.Prog
// TODO(austin) Handle smaller moves. arm and amd64
// distinguish between moves that moves that *must*
// sign/zero extend and moves that don't care so they
// can eliminate moves that don't care without
// breaking moves that do care. This might let us
// simplify or remove the next peep loop, too.
if p.As == ppc64.AMOVD || p.As == ppc64.AFMOVD {
if regtyp(&p.To) {
// Try to eliminate reg->reg moves
if regtyp(&p.From) {
if p.From.Type == p.To.Type {
if copyprop(r) {
excise(r)
t++
} else if subprop(r) && copyprop(r) {
excise(r)
t++
}
}
}
// Convert uses to $0 to uses of R0 and
// propagate R0
if regzer(&p.From) {
if p.To.Type == obj.TYPE_REG {
p.From.Type = obj.TYPE_REG
p.From.Reg = ppc64.REGZERO
if copyprop(r) {
excise(r)
t++
} else if subprop(r) && copyprop(r) {
excise(r)
t++
}
}
}
}
}
}
if t != 0 {
goto loop1
}
/*
* look for MOVB x,R; MOVB R,R (for small MOVs not handled above)
*/
var p1 *obj.Prog
var r1 *gc.Flow
for r := g.Start; r != nil; r = r.Link {
p = r.Prog
switch p.As {
default:
continue
case ppc64.AMOVH,
ppc64.AMOVHZ,
ppc64.AMOVB,
ppc64.AMOVBZ,
ppc64.AMOVW,
ppc64.AMOVWZ:
if p.To.Type != obj.TYPE_REG {
continue
}
}
r1 = r.Link
if r1 == nil {
continue
}
p1 = r1.Prog
if p1.As != p.As {
continue
}
if p1.From.Type != obj.TYPE_REG || p1.From.Reg != p.To.Reg {
continue
}
if p1.To.Type != obj.TYPE_REG || p1.To.Reg != p.To.Reg {
continue
}
excise(r1)
}
if gc.Debug['D'] > 1 {
goto ret /* allow following code improvement to be suppressed */
}
/*
* look for OP x,y,R; CMP R, $0 -> OPCC x,y,R
* when OP can set condition codes correctly
*/
for r := g.Start; r != nil; r = r.Link {
p = r.Prog
switch p.As {
case ppc64.ACMP,
ppc64.ACMPW: /* always safe? */
if !regzer(&p.To) {
continue
}
r1 = r.S1
if r1 == nil {
continue
}
switch r1.Prog.As {
default:
continue
/* the conditions can be complex and these are currently little used */
case ppc64.ABCL,
ppc64.ABC:
continue
case ppc64.ABEQ,
ppc64.ABGE,
ppc64.ABGT,
ppc64.ABLE,
ppc64.ABLT,
ppc64.ABNE,
ppc64.ABVC,
ppc64.ABVS:
break
}
r1 = r
for {
r1 = gc.Uniqp(r1)
if r1 == nil || r1.Prog.As != obj.ANOP {
break
}
}
if r1 == nil {
continue
}
p1 = r1.Prog
if p1.To.Type != obj.TYPE_REG || p1.To.Reg != p.From.Reg {
continue
}
switch p1.As {
/* irregular instructions */
case ppc64.ASUB,
ppc64.AADD,
ppc64.AXOR,
ppc64.AOR:
if p1.From.Type == obj.TYPE_CONST || p1.From.Type == obj.TYPE_ADDR {
continue
}
}
switch p1.As {
default:
continue
case ppc64.AMOVW,
ppc64.AMOVD:
if p1.From.Type != obj.TYPE_REG {
continue
}
continue
case ppc64.AANDCC,
ppc64.AANDNCC,
ppc64.AORCC,
ppc64.AORNCC,
ppc64.AXORCC,
ppc64.ASUBCC,
ppc64.ASUBECC,
ppc64.ASUBMECC,
ppc64.ASUBZECC,
ppc64.AADDCC,
ppc64.AADDCCC,
ppc64.AADDECC,
ppc64.AADDMECC,
ppc64.AADDZECC,
ppc64.ARLWMICC,
ppc64.ARLWNMCC,
/* don't deal with floating point instructions for now */
/*
case AFABS:
case AFADD:
case AFADDS:
case AFCTIW:
case AFCTIWZ:
case AFDIV:
case AFDIVS:
case AFMADD:
case AFMADDS:
case AFMOVD:
case AFMSUB:
case AFMSUBS:
case AFMUL:
case AFMULS:
case AFNABS:
case AFNEG:
case AFNMADD:
case AFNMADDS:
case AFNMSUB:
case AFNMSUBS:
case AFRSP:
case AFSUB:
case AFSUBS:
case ACNTLZW:
case AMTFSB0:
case AMTFSB1:
*/
ppc64.AADD,
ppc64.AADDV,
ppc64.AADDC,
ppc64.AADDCV,
ppc64.AADDME,
ppc64.AADDMEV,
ppc64.AADDE,
ppc64.AADDEV,
ppc64.AADDZE,
ppc64.AADDZEV,
ppc64.AAND,
ppc64.AANDN,
ppc64.ADIVW,
ppc64.ADIVWV,
ppc64.ADIVWU,
ppc64.ADIVWUV,
ppc64.ADIVD,
ppc64.ADIVDV,
ppc64.ADIVDU,
ppc64.ADIVDUV,
ppc64.AEQV,
ppc64.AEXTSB,
ppc64.AEXTSH,
ppc64.AEXTSW,
ppc64.AMULHW,
ppc64.AMULHWU,
ppc64.AMULLW,
ppc64.AMULLWV,
ppc64.AMULHD,
ppc64.AMULHDU,
ppc64.AMULLD,
ppc64.AMULLDV,
ppc64.ANAND,
ppc64.ANEG,
ppc64.ANEGV,
ppc64.ANOR,
ppc64.AOR,
ppc64.AORN,
ppc64.AREM,
ppc64.AREMV,
ppc64.AREMU,
ppc64.AREMUV,
ppc64.AREMD,
ppc64.AREMDV,
ppc64.AREMDU,
ppc64.AREMDUV,
ppc64.ARLWMI,
ppc64.ARLWNM,
ppc64.ASLW,
ppc64.ASRAW,
ppc64.ASRW,
ppc64.ASLD,
ppc64.ASRAD,
ppc64.ASRD,
ppc64.ASUB,
ppc64.ASUBV,
ppc64.ASUBC,
ppc64.ASUBCV,
ppc64.ASUBME,
ppc64.ASUBMEV,
ppc64.ASUBE,
ppc64.ASUBEV,
ppc64.ASUBZE,
ppc64.ASUBZEV,
ppc64.AXOR:
t = variant2as(p1.As, as2variant(p1.As)|V_CC)
}
if gc.Debug['D'] != 0 {
fmt.Printf("cmp %v; %v -> ", p1, p)
}
p1.As = t
if gc.Debug['D'] != 0 {
fmt.Printf("%v\n", p1)
}
excise(r)
continue
}
}
ret:
gc.Flowend(g)
}
// fuseOpMoves looks for moves following 2-operand operations and trys to merge them into
// a 3-operand operation.
//
// For example:
// ADD R1, R2
// MOVD R2, R3
// might become
// ADD R1, R2, R3
func fuseOpMoves(r *gc.Flow) int {
n := 0
for ; r != nil; r = r.Link {
p := r.Prog
switch p.As {
case s390x.AADD:
case s390x.ASUB:
if isConst(&p.From) && int64(int16(p.From.Offset)) != p.From.Offset {
continue
}
case s390x.ASLW,
s390x.ASRW,
s390x.ASRAW,
s390x.ASLD,
s390x.ASRD,
s390x.ASRAD,
s390x.ARLL,
s390x.ARLLG:
// ok - p.From will be a reg or a constant
case s390x.AOR,
s390x.AORN,
s390x.AAND,
s390x.AANDN,
s390x.ANAND,
s390x.ANOR,
s390x.AXOR,
s390x.AMULLW,
s390x.AMULLD:
if isConst(&p.From) {
// these instructions can either use 3 register form
// or have an immediate but not both
continue
}
default:
continue
}
if p.Reg != 0 && p.Reg != p.To.Reg {
continue
}
var move *gc.Flow
rr := gc.Uniqs(r)
for {
if rr == nil || gc.Uniqp(rr) == nil || rr == r {
break
}
pp := rr.Prog
switch copyu(pp, &p.To, nil) {
case _None:
rr = gc.Uniqs(rr)
continue
case _Read:
if move == nil && pp.As == s390x.AMOVD && isGPR(&pp.From) && isGPR(&pp.To) {
move = rr
rr = gc.Uniqs(rr)
continue
}
case _Write:
if move == nil {
// dead code
excise(r)
n++
} else {
for prev := gc.Uniqp(move); prev != r; prev = gc.Uniqp(prev) {
if copyu(prev.Prog, &move.Prog.To, nil) != 0 {
move = nil
break
}
}
if move == nil {
break
}
p.Reg, p.To.Reg = p.To.Reg, move.Prog.To.Reg
excise(move)
n++
// clean up
if p.From.Reg == p.To.Reg && isCommutative(p.As) {
p.From.Reg, p.Reg = p.Reg, 0
}
if p.To.Reg == p.Reg {
p.Reg = 0
}
// we could try again if p has become a 2-operand op
// but in testing nothing extra was extracted
}
}
break
}
}
return n
}
func pushback(r0 *gc.Flow) {
var r *gc.Flow
var b *gc.Flow
p0 := r0.Prog
for r = gc.Uniqp(r0); r != nil && gc.Uniqs(r) != nil; r = gc.Uniqp(r) {
p := r.Prog
if p.As != obj.ANOP {
if !(isReg(&p.From) || isConst(&p.From)) || !isReg(&p.To) {
break
}
if copyu(p, &p0.To, nil) != _None || copyu(p0, &p.To, nil) != _None {
break
}
}
if p.As == obj.ACALL {
break
}
b = r
}
if b == nil {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("no pushback: %v\n", r0.Prog)
if r != nil {
fmt.Printf("\t%v [%v]\n", r.Prog, gc.Uniqs(r) != nil)
}
}
return
}
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("pushback\n")
for r := b; ; r = r.Link {
fmt.Printf("\t%v\n", r.Prog)
if r == r0 {
break
}
}
}
t := *r0.Prog
for r = gc.Uniqp(r0); ; r = gc.Uniqp(r) {
p0 = r.Link.Prog
p := r.Prog
p0.As = p.As
p0.Lineno = p.Lineno
p0.From = p.From
p0.To = p.To
p0.From3 = p.From3
p0.Reg = p.Reg
p0.RegTo2 = p.RegTo2
if r == b {
break
}
}
p0 = r.Prog
p0.As = t.As
p0.Lineno = t.Lineno
p0.From = t.From
p0.To = t.To
p0.From3 = t.From3
p0.Reg = t.Reg
p0.RegTo2 = t.RegTo2
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tafter\n")
for r := b; ; r = r.Link {
fmt.Printf("\t%v\n", r.Prog)
if r == r0 {
break
}
}
}
}
// castPropagation tries to eliminate unecessary casts.
//
// For example:
// MOVHZ R1, R2 // uint16
// MOVB R2, 0(R15) // int8
// Can be simplified to:
// MOVB R1, 0(R15)
func castPropagation(r *gc.Flow) int {
n := 0
for ; r != nil; r = r.Link {
p := r.Prog
if !isMove(p) || !isGPR(&p.To) {
continue
}
// r is a move with a destination register
var move *gc.Flow
for rr := gc.Uniqs(r); rr != nil; rr = gc.Uniqs(rr) {
if gc.Uniqp(rr) == nil {
// branch target: leave alone
break
}
pp := rr.Prog
if isMove(pp) && copyas(&pp.From, &p.To) {
if pp.To.Type == obj.TYPE_MEM {
if p.From.Type == obj.TYPE_MEM ||
p.From.Type == obj.TYPE_ADDR {
break
}
if p.From.Type == obj.TYPE_CONST &&
int64(int16(p.From.Offset)) != p.From.Offset {
break
}
}
move = rr
break
}
if pp.As == obj.ANOP {
continue
}
break
}
if move == nil {
continue
}
// we have a move that reads from our destination reg, check if any future
// instructions also read from the reg
mp := move.Prog
if !copyas(&mp.From, &mp.To) {
safe := false
for rr := gc.Uniqs(move); rr != nil; rr = gc.Uniqs(rr) {
if gc.Uniqp(rr) == nil {
break
}
switch copyu(rr.Prog, &p.To, nil) {
case _None:
continue
case _Write:
safe = true
}
break
}
if !safe {
continue
}
}
// at this point we have something like:
// MOV* const/mem/reg, reg
// MOV* reg, reg/mem
// now check if this is a cast that cannot be forward propagated
execute := false
if p.As == mp.As || isZero(&p.From) || size(p.As) == size(mp.As) {
execute = true
} else if isGPR(&p.From) && size(p.As) >= size(mp.As) {
execute = true
}
if execute {
mp.From = p.From
excise(r)
n++
}
}
return n
}
// constantPropagation removes redundant constant copies.
func constantPropagation(r *gc.Flow) int {
n := 0
// find MOV $con,R followed by
// another MOV $con,R without
// setting R in the interim
for ; r != nil; r = r.Link {
p := r.Prog
if isMove(p) {
if !isReg(&p.To) {
continue
}
if !isConst(&p.From) {
continue
}
} else {
continue
}
rr := r
for {
rr = gc.Uniqs(rr)
if rr == nil || rr == r {
break
}
if gc.Uniqp(rr) == nil {
break
}
pp := rr.Prog
t := copyu(pp, &p.To, nil)
switch t {
case _None:
continue
case _Read:
if !isGPR(&pp.From) || !isMove(pp) {
continue
}
if p.From.Type == obj.TYPE_CONST {
v := applyCast(p.As, p.From.Offset)
if isGPR(&pp.To) {
if int64(int32(v)) == v || ((v>>32)<<32) == v {
pp.From.Reg = 0
pp.From.Offset = v
pp.From.Type = obj.TYPE_CONST
n++
}
} else if int64(int16(v)) == v {
pp.From.Reg = 0
pp.From.Offset = v
pp.From.Type = obj.TYPE_CONST
n++
}
}
continue
case _Write:
if p.As != pp.As || p.From.Type != pp.From.Type {
break
}
if p.From.Type == obj.TYPE_CONST && p.From.Offset == pp.From.Offset {
excise(rr)
n++
continue
} else if p.From.Type == obj.TYPE_FCONST {
if p.From.Val.(float64) == pp.From.Val.(float64) {
excise(rr)
n++
continue
}
}
}
break
}
}
return n
}
/*
* the idea is to substitute
* one register for another
* from one MOV to another
* MOV a, R1
* ADD b, R1 / no use of R2
* MOV R1, R2
* would be converted to
* MOV a, R2
* ADD b, R2
* MOV R2, R1
* hopefully, then the former or latter MOV
* will be eliminated by copy propagation.
*
* r0 (the argument, not the register) is the MOV at the end of the
* above sequences. This returns 1 if it modified any instructions.
*/
func subprop(r0 *gc.Flow) bool {
p := r0.Prog
v1 := &p.From
if !regtyp(v1) {
return false
}
v2 := &p.To
if !regtyp(v2) {
return false
}
for r := gc.Uniqp(r0); r != nil; r = gc.Uniqp(r) {
if gc.Uniqs(r) == nil {
break
}
p = r.Prog
if p.As == obj.AVARDEF || p.As == obj.AVARKILL {
continue
}
if p.Info.Flags&gc.Call != 0 {
return false
}
if p.Info.Flags&(gc.RightRead|gc.RightWrite) == gc.RightWrite {
if p.To.Type == v1.Type {
if p.To.Reg == v1.Reg {
copysub(&p.To, v1, v2, true)
if gc.Debug['P'] != 0 {
fmt.Printf("gotit: %v->%v\n%v", gc.Ctxt.Dconv(v1), gc.Ctxt.Dconv(v2), r.Prog)
if p.From.Type == v2.Type {
fmt.Printf(" excise")
}
fmt.Printf("\n")
}
for r = gc.Uniqs(r); r != r0; r = gc.Uniqs(r) {
p = r.Prog
copysub(&p.From, v1, v2, true)
copysub1(p, v1, v2, true)
copysub(&p.To, v1, v2, true)
if gc.Debug['P'] != 0 {
fmt.Printf("%v\n", r.Prog)
}
}
v1.Reg, v2.Reg = v2.Reg, v1.Reg
if gc.Debug['P'] != 0 {
fmt.Printf("%v last\n", r.Prog)
}
return true
}
}
}
if copyau(&p.From, v2) || copyau1(p, v2) || copyau(&p.To, v2) {
break
}
if copysub(&p.From, v1, v2, false) || copysub1(p, v1, v2, false) || copysub(&p.To, v1, v2, false) {
break
}
}
return false
}
func pushback(r0 *gc.Flow) {
var r *gc.Flow
var p *obj.Prog
var b *gc.Flow
p0 := (*obj.Prog)(r0.Prog)
for r = gc.Uniqp(r0); r != nil && gc.Uniqs(r) != nil; r = gc.Uniqp(r) {
p = r.Prog
if p.As != obj.ANOP {
if !regconsttyp(&p.From) || !regtyp(&p.To) {
break
}
if copyu(p, &p0.To, nil) != 0 || copyu(p0, &p.To, nil) != 0 {
break
}
}
if p.As == obj.ACALL {
break
}
b = r
}
if b == nil {
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("no pushback: %v\n", r0.Prog)
if r != nil {
fmt.Printf("\t%v [%v]\n", r.Prog, gc.Uniqs(r) != nil)
}
}
return
}
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("pushback\n")
for r := (*gc.Flow)(b); ; r = r.Link {
fmt.Printf("\t%v\n", r.Prog)
if r == r0 {
break
}
}
}
t := obj.Prog(*r0.Prog)
for r = gc.Uniqp(r0); ; r = gc.Uniqp(r) {
p0 = r.Link.Prog
p = r.Prog
p0.As = p.As
p0.Lineno = p.Lineno
p0.From = p.From
p0.To = p.To
if r == b {
break
}
}
p0 = r.Prog
p0.As = t.As
p0.Lineno = t.Lineno
p0.From = t.From
p0.To = t.To
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
fmt.Printf("\tafter\n")
for r := (*gc.Flow)(b); ; r = r.Link {
fmt.Printf("\t%v\n", r.Prog)
if r == r0 {
break
}
}
}
}
// copy1 replaces uses of v2 with v1 starting at r and returns 1 if
// all uses were rewritten.
func copy1(v1 *obj.Addr, v2 *obj.Addr, r *gc.Flow, f bool) bool {
if uint32(r.Active) == gactive {
if gc.Debug['P'] != 0 {
fmt.Printf("act set; return 1\n")
}
return true
}
r.Active = int32(gactive)
if gc.Debug['P'] != 0 {
fmt.Printf("copy1 replace %v with %v f=%v\n", gc.Ctxt.Dconv(v2), gc.Ctxt.Dconv(v1), f)
}
for ; r != nil; r = r.S1 {
p := r.Prog
if gc.Debug['P'] != 0 {
fmt.Printf("%v", p)
}
if !f && gc.Uniqp(r) == nil {
// Multiple predecessors; conservatively
// assume v1 was set on other path
f = true
if gc.Debug['P'] != 0 {
fmt.Printf("; merge; f=%v", f)
}
}
switch t := copyu(p, v2, nil); t {
case 2: /* rar, can't split */
if gc.Debug['P'] != 0 {
fmt.Printf("; %v rar; return 0\n", gc.Ctxt.Dconv(v2))
}
return false
case 3: /* set */
if gc.Debug['P'] != 0 {
fmt.Printf("; %v set; return 1\n", gc.Ctxt.Dconv(v2))
}
return true
case 1, /* used, substitute */
4: /* use and set */
if f {
if gc.Debug['P'] == 0 {
return false
}
if t == 4 {
fmt.Printf("; %v used+set and f=%v; return 0\n", gc.Ctxt.Dconv(v2), f)
} else {
fmt.Printf("; %v used and f=%v; return 0\n", gc.Ctxt.Dconv(v2), f)
}
return false
}
if copyu(p, v2, v1) != 0 {
if gc.Debug['P'] != 0 {
fmt.Printf("; sub fail; return 0\n")
}
return false
}
if gc.Debug['P'] != 0 {
fmt.Printf("; sub %v->%v\n => %v", gc.Ctxt.Dconv(v2), gc.Ctxt.Dconv(v1), p)
}
if t == 4 {
if gc.Debug['P'] != 0 {
fmt.Printf("; %v used+set; return 1\n", gc.Ctxt.Dconv(v2))
}
return true
}
}
if !f {
t := copyu(p, v1, nil)
if t == 2 || t == 3 || t == 4 {
f = true
if gc.Debug['P'] != 0 {
fmt.Printf("; %v set and !f; f=%v", gc.Ctxt.Dconv(v1), f)
}
}
}
if gc.Debug['P'] != 0 {
fmt.Printf("\n")
}
if r.S2 != nil {
if !copy1(v1, v2, r.S2, f) {
return false
}
}
}
return true
}
// fuseClear merges memory clear operations.
//
// Looks for this pattern (sequence of clears):
// MOVD R0, n(R15)
// MOVD R0, n+8(R15)
// MOVD R0, n+16(R15)
// Replaces with:
// CLEAR $24, n(R15)
func fuseClear(r *gc.Flow) int {
n := 0
var align int64
var clear *obj.Prog
for ; r != nil; r = r.Link {
// If there is a branch into the instruction stream then
// we can't fuse into previous instructions.
if gc.Uniqp(r) == nil {
clear = nil
}
p := r.Prog
if p.As == obj.ANOP {
continue
}
if p.As == s390x.AXC {
if p.From.Reg == p.To.Reg && p.From.Offset == p.To.Offset {
// TODO(mundaym): merge clears?
p.As = s390x.ACLEAR
p.From.Offset = p.From3.Offset
p.From3 = nil
p.From.Type = obj.TYPE_CONST
p.From.Reg = 0
clear = p
} else {
clear = nil
}
continue
}
// Is our source a constant zero?
if !isZero(&p.From) {
clear = nil
continue
}
// Are we moving to memory?
if p.To.Type != obj.TYPE_MEM ||
p.To.Index != 0 ||
p.To.Offset >= 4096 ||
!(p.To.Name == obj.NAME_NONE || p.To.Name == obj.NAME_AUTO || p.To.Name == obj.NAME_PARAM) {
clear = nil
continue
}
size := int64(0)
switch p.As {
default:
clear = nil
continue
case s390x.AMOVB, s390x.AMOVBZ:
size = 1
case s390x.AMOVH, s390x.AMOVHZ:
size = 2
case s390x.AMOVW, s390x.AMOVWZ:
size = 4
case s390x.AMOVD:
size = 8
}
// doubleword aligned clears should be kept doubleword
// aligned
if (size == 8 && align != 8) || (size != 8 && align == 8) {
clear = nil
}
if clear != nil &&
clear.To.Reg == p.To.Reg &&
clear.To.Name == p.To.Name &&
clear.To.Node == p.To.Node &&
clear.To.Sym == p.To.Sym {
min := clear.To.Offset
max := clear.To.Offset + clear.From.Offset
// previous clear is already clearing this region
if min <= p.To.Offset && max >= p.To.Offset+size {
excise(r)
n++
continue
}
// merge forwards
if max == p.To.Offset {
clear.From.Offset += size
excise(r)
n++
continue
}
// merge backwards
if min-size == p.To.Offset {
clear.From.Offset += size
clear.To.Offset -= size
excise(r)
n++
continue
}
}
// transform into clear
p.From.Type = obj.TYPE_CONST
p.From.Offset = size
p.From.Reg = 0
p.As = s390x.ACLEAR
clear = p
align = size
}
return n
}